1. Field of the Invention
This invention relates in general to the field of telecommunications and, more particularly, to a method for managing radio resources at the access network level in a UMTS mobile communication network in packet mode and in circuit mode.
Thus, the method according to the invention is intended for application to mobile networks using the UMTS technology, standardised within the framework of the 3GPP standard. For the sake of not overloading the description, a glossary comprising definitions for all of the acronyms used is provided at the end of the description, to which the reader may usefully refer.
2. Description of the Related Art
The UMTS standard specifies a new mobile access network: UTRAN, which makes it possible to offer subscribers of a mobile operator access to IP-based services (electronic messaging, downloading of files, web or WAP site consultation) or circuit services (telephony, video-telephony). At the present time, UMTS is being phased-in, in various versions also referred to as “releases,” according to the English terminology, and in particular the version called Release 99, to which the following description refers more particularly.
Architecturally speaking, the UMTS network can be divided into two sub-networks the core network CN and the radio access network, also called UTRAN, as shown in FIG. 1.
The access network includes a plurality of Node-B radio base stations, provided for communicating with user equipment UE through a radio interface using radio resources allocated by an RNC controller. The hierarchical architecture in which one entity controls several lower-level entities is identical to the GSM radio access network. The RNC radio network controller therein holds the position of the GSM base station controller (BSC). However, the radio technologies used for transporting information are different.
As concerns the UMTS core network CN, it includes two separate systems: the circuit system Cs, which includes all of the services associated with telephony, and the packet system PS, which includes all of the services associated with packet switching.
At the core network level is found the HLR, which is a database common to both systems, wherein is stored the information relating to each subscriber of the network's operator: the subscriber's telephone number, the mobile identity as well as the subscription information. The HLR also contains, among other things, the quality of service information associated with the subscribers and services, which will be defined further on in the description. Thus, it is from this database that the mobile subscribers within the network are managed.
The core network also hosts the MSC circuit switches and the SGSN packet switches. These service nodes of the core network manage the communication link with the access network. They store the subscriber profile coming from the HLK and monitor the network resources requested by the subscriber.
At the packet system level, the SGSN is associated with another service node, the GGSN, which acts more particularly as a gateway to the outside packet-switching networks (Internet, etc. . . . ). As concerns the packet system, the UMTS core network is thus interconnected with the outside via a gateway, the GGSN service node, which contains the routing information enabling the mobile telephone to communicate with an external network, particularly the Internet network, while at the same time ensuring security. In order to be able to send information to the mobile telephone, the GGSN then uses the other service node, the SGSN, which manages mobility at the core network level, authentication and encryption. These network elements integrate IP router functions and constitute an IP-type network.
At the circuit system level, and in the same way as explained in relation to the packet system, the MSC is associated with another service node, the GMSC, serving as a gateway to the stationary networks of the RNC type, RNIS type, etc.
In Release 99, all of the UMTS services are supported by four standardised classes of traffic as follows: “Conversational”, “Streaming”, “Interactive” and “Background”.
The “Conversational” and “Streaming” classes are provided primarily for transporting real-time streams such as voice or video. However, for the “Streaming” class, corresponding to a use of the type where a user is looking at (or listening to) a real-time video (or audio) stream, the data transfer time restraints are fewer than for the “Conversational” class.
The “Interactive” and “Background” classes correspond to non-real-time services and are themselves provided to be used within the framework of traditional Internet applications such as navigation, electronic mail, and FTP applications. Being non-real-time, these latter classes offer a much better error rate thanks to retransmission and encoding methods.